Iberian ribbed newt

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Iberian ribbed newt
Pleurodeles waltl in an aquarium

Least Concern  (IUCN 3.1)[1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Urodela
Family: Salamandridae
Genus: Pleurodeles
Species:
P. waltl
Binomial name
Pleurodeles waltl
Distribution in the Iberian peninsula and the Maghreb
Synonyms

Pleurodeles waltlii (incorrect spelling)

The Iberian ribbed newt (Pleurodeles waltl), also known

Pleurodelinae of the family Salamandridae. The species is native to the central and southern Iberian Peninsula and Morocco.[2]
It is the largest European newt species. It is known for its defense mechanisms where their sharp ribs puncture through its sides when in a defensive state, and as such is also called the sharp-ribbed newt and the sharp-ribbed salamander.

This species should not be confused with a different species with a similar common name, the Iberian newt (

Lissotriton boscai
).

Description

The Iberian ribbed newt typically have 8 to 10 tubercles that look like orange warts running down each side. Through these, its sharp ribs can puncture through the stretched skin. The size of their ribs are larger than most other salamanders. The ribs act as a defense mechanism, causing little harm to the newt. Iberian ribbed newts generally try to run away from predators, but if they cannot escape they resort to this mechanism.[3] It could be considered as a primitive and rudimentary system of envenomation, but is completely harmless to humans.[4] At the same time as pushing its ribs out the newt begins to secrete a milky and viscous poison from special glands on its body. The poison primarily appears on the neck, the dorsal and lateral trunk, and on the tail. The poison coated ribs create a highly effective stinging mechanism, injecting toxins through the thin skin in predator's mouths. The newt's immune system, collagen coated ribs, and secretion of antimicrobial peptides released from specialized cutaneous glands mean the pierced skin quickly regrows without infection.[5]

Similar to most amphibians, Iberian ribbed newts are born in the water and breathe through their gills during the larvae phase. Once they start to grow limbs, they lose their gills and gain the ability to survive on land as well as in water. [6] P. waltl is more aquatic-dwelling than many other European tailed amphibians. Though it is quite able to walk on land, most rarely leave the water, living usually in ponds, cisterns, and ancient village wells that were common in Portugal and Spain in the past. They have also been found inhabiting areas in northwestern Africa. It prefers cool, quiet, and deep waters, where it feeds on insects, aquatic molluscs,[7] worms, and tadpoles. During warmer seasons some of these water sources dry up and the newts migrate to moist areas under rocks or with vegetation. In order to adapt to the different types stimuli found in these different habitats, it has been found that Iberian ribbed newts possess physiological and behavioral plasticity. [6]

In the wild, this amphibian grows to a total length (tail included) of 30 cm (12 in),

dorsally
, and lighter gray on its ventral side, with rust-colored small spots where its ribs can protrude. This newt has a flat, spade-shaped head and a long tail, which is about half its body length. Males are more slender and usually smaller than females. The larvae have bushy external gills and usually paler color patterns than the adults.

Sex determination

Sex determination in P. waltl is regulated by

Hormones play an important role during the sex determination process, and the newts can be manipulated to change sex by adding hormones or hormone-inhibitors to the water in which they are reared.[9]

Aromatase, an estrogen-synthesizing enzyme which acts as a steroid hormone, plays a key role in sex determination in many non-mammalian vertebrates, including the Iberian ribbed newt.[9] It is found in higher levels in the gonad–mesonephros complexes in ZW larvae than in their ZZ counterparts, although not in heat-treated ZW larvae. The increase occurs near the final stages of which their sex can be determined by temperature (stage 52).

Conservation

As of an assessment in October 2020, the

industrial contamination, golf courses, and infrastructure development. It has largely disappeared from coastal areas in Iberia and Morocco close to concentrations of tourism and highly populated areas such as Madrid's outskirts. Introduced fish such as the largemouth bass and crayfish (Procambarus clarkii) are known to prey on the eggs and larvae of this species, and are implicated in its decline. Mortality on roads has been reported to be a serious threat to some populations.[10]

Space experiments

bion satellite
shown here, first carried the Iberian ribbed newt into space. The circular viewport seen on this craft was installed for its display in a space museum.

P. waltl has been studied in space on at least six missions. The first Iberian ribbed newts were sent to space in 1985 on board

Bion 10[12][13] also carried the newts on board, as did Bion 11[14]
in 1996.

P. waltl research was continued later in 1996 by French-led experiments on the

Foton-M2[16]
also carried the Iberian ribbed newt in 2005.

Iberian ribbed newts in an aquarium (on Earth)

The Iberian ribbed newt was chosen because it is a good

ontogenesis can be observed, from the oocyte
to swimming tailbud embryos or larvae.

Studies looked at the Iberian ribbed newt's ability to regenerate (which was faster in space overall, and up to two times as fast in early stages),[14] as well as the stages of development and reproduction in space.[18]

On the ground, studies of hypergravity (up to 3g) on P. waltl fertilisation have also been conducted,[19] as well as on the fertility of the space-born newts once they arrived back on Earth (they were fertile, and without problems).[15]

Similar microgravity experiments have also been conducted for other species, namely the frog species Hyla japonica, and no effects on long term health are similarly observed.

Regeneration

P. waltl is a model organism for the study of adult regeneration. Similar to other salamanders, P. waltl can regenerate lost limbs, injured heart tissue, and lesioned brain cells, in addition to other body parts such as the eye lens and the spinal cord. The 20 Gb genome of P. waltl has been sequenced to facilitate research into the genetic basis of this regenerative ability.[20] Regeneration is able to occur due to the newt's specialized progenitor cells and the transduction of their somatic cells, which act like stem cells.[21] Stem cells repair damaged tissue and contribute to regeneration effects. In most organisms, the efficiency of the function of these stem cells decrease, but in some organisms like P. waltl, this degeneration does not occur. It has been shown that during lens regeneration in P. waltl, they upregulate their DNA repair and ROS-related genes. [22]

To study the lens regeneration of P. waltl, the eye lens is removed in a surgery called a lentectomy. After the lens is removed, new lens epithelial cells start to differentiate and result in the growth of secondary lens fibers that surround the primary lens fibers. What is unique about P. waltl lens regeneration is that the newly formed lens fiber has different organelle composition compared to the primary lens fiber. This results in different scattering properties, but does not effect the regeneration abilities. After the lens has finished regenerating, it separates from the dorsal iris and moves to the position of the original iris, which is a necessary step to allow the newt to regain functional vision. While aging does not effect the regeneration capacity of P. waltl, it does effect the regeneration processes and timeline. The newt larvae regenerate the eye lens in a shorter time period in comparison to juvenile and adult newts. [23]

See also

References

  1. doi:10.2305/IUCN.UK.2023-1.RLTS.T59463A89708437.en
    . Retrieved 18 March 2024.
  2. ^ Frost, Darrel R. (2014). "Pleurodeles waltl Michahelles, 1830". Amphibian Species of the World: an Online Reference. Version 6.0. American Museum of Natural History. Retrieved 11 March 2015.
  3. ISSN 1469-7998
    .
  4. ^ Bruna Azara, C. (1995). "Vertebrados terrestres venenosos peligrosos para el ser humano en España" (PDF). Boletín de la Sociedad Entomológica Aragonesa (S.E.A.). 11: 32–40. (in Spanish).
  5. ^ http://cabinetoffreshwatercuriosities.com/2010/11/11/spanish-ribbed-newt/ Archived 2013-10-03 at the Wayback Machine Spanish ribbed newt - Pleurodeles waltl, The BioFresh Cabinet of Freshwater Curiosities
  6. ^
    PMID 39837267
    .
  7. ^ "AmphibiaWeb – Pleurodeles waltl".
  8. ISBN 0-00-219318-3
    . 272 pp.
  9. ^
    PMID 15591030
    .
  10. ^ IUCN SSC Amphibian Specialist Group. 2023. Pleurodeles waltl. The IUCN Red List of Threatened Species 2023: e.T59463A89708437. https://dx.doi.org/10.2305/IUCN.UK.2023-1.RLTS.T59463A89708437.en. Accessed on 9 March 2025.
  11. ^ Mitashov, V.; et al. Lens and limb regeneration in newt during and after 13-day long spaceflight [1][permanent dead link]
  12. Bibcode:1994ESASP.366..181G
    .
  13. Bibcode:1994ESASP.366..171D
    .
  14. ^
    PMID 12528722
    .
  15. ^
    S2CID 23149867
    .
  16. ^ Domaratskaya et al., Studies on hemopoietic tissue of ribbed newt, Pleurodeles waltl, after the flight on board Russian satellite "Foton-M2" in 2005 [2]
  17. PMID 11799990
    .
  18. ^ Dournon C & Houillon C 1985 Thermosensibilité de la différenciation sexuelle chez l’Amphibien Urodè le, Pleurodeles waltlii Michah. Conditions pour obtenir l’inversion du phénotype sexuel de toutes les femelles génétiques sous l’action de la température d’élevage. Reproduction Nutrition Développement 25 671–688.
  19. PMID 10906064
    .
  20. PMID 29273779
    .
  21. PMID 24512711
    , retrieved 2025-03-10
  22. PMID 23613853
    .
  23. PMID 37055300
    .

Further reading

  • Michahelles, [K]. (1830). "Neue südeuropäische Amphibien ". Isis von Oken. 23: 189–195. (Pleurodeles waltl, new species, p. 191). (in German).
Wikispecies has information related to Pleurodeles waltl.
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